Vocabulary is an important component of language proficiency which provides the basis for learners’ performance in other skills. But, since vocabulary learning seems to be so demanding, learners tend to forget newly-learnt words quite soon. In order to identify vocabulary learning conditions which can produce a more lasting effect, this study investigated the effect of three kinds of gloss conditions, that is traditional non-CALL marginal gloss, audio gloss, and extended audio gloss, on vocabulary gain of EFL learners. To this end, three experimental and one control groups, each comprising 15 participants, took part in the current study. In order to ensure that the participants were from the right proficiency level, KET (Key English Test) was used as the homogenizing tool. Participants in each group read two unseen passages under one of the three mentioned conditions for experimental groups, with no gloss offered for control group. They all completed one pre-test, one reading session, one post-test, and one delayed post-test of vocabulary. The data were analyzed using t-tests and one-way ANOVAs for both immediate and delayed post-tests. Statistical analyses of the results revealed that the audio gloss group, who were provided with the voice of a speaker to read the meaning of the target word, and extended audio gloss group, who had access to audio gloss as well as L2 English example, both significantly outperformed the other groups in terms of vocabulary acquisition in both the immediate retention and in the delayed retention of key words. Further results and implications are discussed in the paper.
